SOLUTION: If given: u <-1, 7> and v <4, -3> then what's the measure of the angle between them? A.) {{{ 45 }}} B.) {{{ 135 }}} C.) {{{ 225 }}} D.) B and C

Algebra ->  Finance -> SOLUTION: If given: u <-1, 7> and v <4, -3> then what's the measure of the angle between them? A.) {{{ 45 }}} B.) {{{ 135 }}} C.) {{{ 225 }}} D.) B and C      Log On


   

Question 1070962: If given: u <-1, 7> and v <4, -3> then what's the measure of the angle between them?
A.) +45+
B.) +135+
C.) +225+
D.) B and C
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Use the dot product,
a%2Ab=abs%28a%29abs%28b%29cos%28theta%29
cos%28theta%29=%28a%2Ab%29%2F%28abs%28a%29%2Aabs%28b%29%29

cos%28theta%29=%28-25%29%2F%28sqrt%281%2B49%29sqrt%2816%2B9%29%29
cos%28theta%29=%28-25%29%2F%285sqrt%282%29%2A5%29
cos%28theta%29=%28-1%29%2F%28sqrt%282%29%29
cos%28theta%29=-sqrt%282%29%2F2
theta=135